The invention relates to a damper which generates a damping torque only when a rotor rotates or turns relative to a housing in a damping torque generating direction.
Conventionally, the above-mentioned damper includes a cylindrical housing; a rotor having a cylindrical shaft portion and wing portions formed on a part of the shaft portion and extending in a radial direction, the rotor being rotatably housed in the housing; control valve members, each being disposed between the housing and the part of the shaft portion and covering the wing portion; and a viscous fluid filled inside the housing. In this damper, the rotor rotates relative to the housing in a damping torque generating direction, so that the control valve members move relative to the rotor in a counter-damping torque generating direction, and block circulation passages for the viscous fluid. Accordingly, the damper assumes a damping state generating a damping torque. Also, the rotor rotates relative to the housing in the counter-damping torque generating direction, so that the control valve members move relative to the rotor in the damping torque generating direction, and open the circulation passages for the viscous fluid. Accordingly, the damper assumes a non-damping state. (Refer to Japanese Patents No. 2882109, No. 3125416 and No. 3053156).
However, the above-mentioned conventional damper is a one-way damper wherein the wing portions are formed in a symmetric shape with respect to a rotational direction relative to a straight line extending radially from the shaft portion; the control valve members are formed in a C-shape in a cross sectional view; and the moving distance of the control valve members is enlarged. As a result, the moving distance relative to the rotor (wing portions) of the control valve members becomes longer during a reverse movement from the damping state to the non-damping state, or from the non-damping state to the damping state.
Therefore, during the reverse movement from the damping state to the non-damping state, or from the non-damping state to the damping state, the play (moving distance) of the control valve members becomes longer, so that response of the control valve members deteriorates.
This invention is made in order to solve the above-mentioned problem, and an object of the invention is to provide a damper, in which the play (moving distance) of the control valve member can be shortened, so that it is possible to provide a damper with excellent response.
Further objects and advantages of the invention will be apparent from the following description of the invention.